The shortages are also hitting restaurant chains. Sandwich chain Pret a Manger said it had been using alternative varieties of leaf in its salads, such as Lollo Rosso and Frisse. Meanwhile, one extremely hopeful seller put a box of lettuces up for sale on Gumtree for £50 in a bid to cash in while eBay had listings for iceberg lettuces for between 99p and £4.99.

Industry suppliers said fresh herbs such as coriander, parsley, mint and thyme were also affected by shortages.

A spokesman for Global Fruit & Veg, a Birmingham-based importer which suppliers local retailers, markets and wholesalers, said it had begun flying in herbs from Egypt and Jordan for the first time because it could not get sufficient supplies from Spain. Wholesale prices have shot up by about 70% because of the supply squeeze.

Supermarket shelves have been left empty and prices soared to as much as three times their usual price as supplies from Murcia, where more than 80% of many salad and vegetable crops sold in the UK usually come from over the winter, have slumped.

Iceberg lettuce supplies to the UK have been particularly affected as it is extremely sensitive to temperature. More than90% of icebergs sold in the UK during the winter are grown in Spain.

Growers began warning of shortages in December when the normally dry region was hit by flooding which washed away entire crops of some vegetables. The situation worsened when the heaviest snow in more than 30 years fell on the region.

Few lettuces or other tender crops are grown in the UK over the winter because it is neither economic nor environmentally sustainable because they would require heated greenhouses or polytunnels.

An Asda spokesperson said: “We’re doing everything we can to support our growers and get back up to full supply as quickly as possible, but we apologise if we’re running a bit low on some products in the short term.”

Like all the other supermarkets, Asda is also flying in lettuces from the US to boost availability.

Traders at the New Covent Garden wholesale market in London, which supplies restaurants, markets and retailers all around the country, said trade was tough.

Gareth Lewis of Harwood’s of London said: “Basically it’s everything coming from Spain and for some people here that’s as much as 60% of their produce. It means that on aubergines, iceberg lettuce, cucumbers – we’re either not making any profit or losing money. It’s very stressful, it’s a big headache to be honest.”

Lewis said that normally iceberg lettuce would cost him about £6 a box, but he is having to import American lettuce for £14. Aubergines have leapt from £6-8 a box to £24 while boxes of courgettes that usually cost £4-6 now cost £22. He described getting all attempts to source spinach as “a challenge”.

While his staff boxed up bright rainbow chard, plump vine tomatoes and a few prized iceberg lettuces for restaurant clients, including those of star chef Yotam Ottolenghi, wholesaler Dan McCullough explained that he is taking some of the financial hit rather than pass on the full cost to clients. “I’ve never seen anything like this before,” says the wholesaler, who set up First Choice Produce 40 years ago.

McCullough said import prices had already risen by 10%, before the weather problems, as a result of the fall in the pound caused by the Brexit vote. “Occasionally you get a problem with one product, but this many for this amount of time is unheard of.”

But there could be a silver lining says Vernon Mascarenhas, head of sales and marketing at First Choice Produce. His company is advising clients to buy alternative seasonal crops, such as savoy cabbage and purple sprouting broccoli grown in the UK. “We have plenty of vegetables in the UK, so rather than rely on foreign produce we could see people moving to homegrown produce. Maybe it’s a blessing in disguise.”

Meanwhile José Ugarrio, a technical expert at Asaja, Spain’s largest farming association, said that the worst of the cold, wet weather that hit vegetable producers in the country had now passed. “Production is gradually recovering,” he said, “But it’s going to take a bit longer for broccoli and lettuce to get back into production.”